Abstract
M.Ing.
This thesis describes a full design project of a processor based sophisticated measurement instrument - the
datalogger. It covers the theoretical approach to the design project followed with hardware and software design.
Many nonstandard solutions in hardware and software parts are used to approach a target, and they are fully
described.
The world that surrounds us today is full of products based on science and technology knowledge. These
products are part of everyday life. The development of science and technology is very much depend upon a parallel
development of measurement techniques and instruments. Measurement and the technology of measurement called
instrumentation, serves not only science but all branches of engineering, medicine and almost every sphere of human
life. Measuring instruments are used in the monitoring and control of processes and operations, too. Most specialised
instruments, such as the datalogger, are used in experimental, research and develop science and engineering work.
This thesis is organised into six chapters. The dataloger position in the measurement instruments tree is
shown in the first chapter. The electronics design philosophy follows in the next chapter. It covers the most common
problems found when the new design project starts. The global design strategy with brief description of all steps
follows. The second chapter contains the datalogger project history, the reasons for going into the project, and the
requests of the new device, too. At the end of this chapter the basic work principle of the datalogger is described to
allow an easily following applied solutions.
The third chapter covers all datalogger design specialities that make the datalogger design different from
the design of other measurement instruments. It starts with remote sensors problems and problems commonly
connected to the input stage of similar systems. The second half of this chapter analyses the instrument precision and
error sources. There are several different methods that precision can be increased. Two methods applied here,
reducing measurement range and oversampling with noise, are briefly described.
The forth chapter interpretates the design of the processor board. It starts with a general microcontroller
overview, describing the reasons for selecting the Hitachi microcontroller H8/532. The most important
microcontroller characteristics are shown, too. The second part of this chapter contains the organisation, connections
and contents of other electronics blocks in the processor board. At the end of this chapter the processor board
schematic and full characteristics are given.
The datalogger's hardware is described in the fifth chapter. The basic work principles of the various
hardware parts are given in the beginning. The hardware is broken down and described in the following way: power
electronics, digital control, signal processing part, and interface cards. All parts are covered with detailed
descriptions of design circuit and the following calculation.
The last chapter shows the software for the datalogger. It starts with the mathematical calculation principle
developed and used in the datalogger. The customer part which follows covers software and hardware part relation
between user and datalogger. One of the datalogger's software speciality is organisation of RAM space which allows
high software flexibility of the datalogger as a measurement instrument. At the end the full datalogger program
organisation is given on a global level.